Quantum Dot Mediated Bead-Based Assays for Continuous Biomarker Monitoring in Diabetes and Ex Vivo Lung Perfusion Systems

Abstract

The continuous monitoring of biomolecules such as hormones, polypeptides, and monosaccharides can provide crucial information about biological systems, leading to a better understanding of human physiology and an improved ability to diagnose and treat complex, multisystemic illnesses. There is a lack of technological advancements that can measure a diverse range of biomarkers with the necessary sensitivity, specificity, and temporal resolution at physiologically relevant concentrations, in a multiplexed manner. Traditionally, enzyme-linked immunosorbent assays (ELISAs) have been used to detect protein biomarkers, while small carbohydrate biomarkers like glucose and lactate levels are measured enzymatically. However, these methods are time consuming, do not offer real-time or multiplexed detection, and require substantial amounts of reagents, sophisticated detection instrumentation, and trained personnel to perform. This study focuses on developing assays for use in two diseases with significant clinical impact: diabetes, where the detection of hormones insulin and glucagon is demonstrated, and ex vivo lung perfusion, where the detection of small molecules lactate and glucose is shown. The system utilizes Quantum Dot mediated Bead-Based Assays (BQA) with microfluidic modules to create a real-time ELISA (QIRT-ELISA) platform for continuous and multiplexed detection of diverse biomarkers in heterogeneous biological matrices. This system surpasses traditional ELISAs by significantly improving sensitivity, specificity, and measurement times, while also enabling multiplexing through the use of quantum dots and their unique optical properties to extract multiple discrete emission spectra signals from targets of interest with a single UV excitation laser. Validation experiments demonstrate that QIRT-ELISA can detect insulin and glucagon in the low picomolar range in whole blood, and lactate and glucose in the low millimolar range in ex vivo lung perfusate. Continuous measurements of insulin and glucagon in vivo in rats undergoing glucose tolerance tests further validate the platform, showing comparable results to conventional ELISA. Thus, the platform presents unique advancements in continuous monitoring technology that can be applied clinically to improve personalized precision medicine and enhance patient outcomes. We believe that the platform can be further developed to encompass a wider range of biomarkers, making it universally applicable across various clinical settings.